Refractive Uses of Layered and Two-Dimensional Materials for Integrated Photonics

The scientific community has witnessed tremendous expansion of research on layered (i.e., two-dimensional, 2D) materials, with increasing recent focus on applications to photonics. Layered materials are particularly exciting for manipulating light in the confined geometry of photonic integrated circuits, where key material properties include strong and controllable light–matter interaction and limited optical loss. Layered materials feature tunable optical properties, phases that are promising for electro-optics, and a panoply of polymorphs that suggest a rich design space for highly nonperturbative photonic integrated devices based on phase-change functionality. All of these features are manifested in materials with band gap above the photonics-relevant near-infrared (NIR) spectral band (∼ 0.5–1 eV), meaning that they can be harnessed in refractive (i.e., nonabsorptive) applications.